The objective of this application is to examine the effects of certain dietary elements on the risk of Barrett's esophagus (BE) and gastroesophageal reflux disease (GERD). Barrett's esophagus is a precursor to esophageal adenocracinoma, a cancer that is experiencing a dramatic increase in its incidence in the United States. Because of this cancer's low survival rate and poor response to treatments, identification of modifiable risk factors inessential in preventing this lethal disease. GERD is one of the major risk factors for esophageal adenocarcinoma and BE. GERD is also the most common diseases among Americans, and it symptoms strongly affects the quality of life of those affected. Dietary modification is routinely advised for GERD patients, though there has been little epidemiological evidence on its effectiveness. Better understanding of the effects of diet on GERD would not only help improve the quality of life of affected individuals, but also reduce the risk of Barrett's esophagus and esophageal adenocarcinoma. The proposed study is a continuation from the applicant's doctoral dissertation research where she found a strong inverse association between fruits and vegetables and the risk of BE. This study will utilize existing data obtained from a population-based case-control study of Barrett's esophagus conducted using Northern California Kaiser Permanente population during the years 2004-2005. Subjects include 296 incident BE cases, 308 GERD controls, and 309 population controls. Controls were frequency matched by age, sex, and location of the diagnosis. At in-home interview, each subject provided information using validated food frequency questionnaire and GERD symptom questionnaire;anthropometric measures and blood samples were also collected by trained interviewers. The specific aims are as follows: 1) To evaluate the effects of dietary fat (total and saturated), protein (animal vs. vegetable), cholesterol, charbroiled food, and fiber on the risk of Barrett's esophagus. 2) To evaluate the effects of fatty foods, caffeine, chocolate, alcohol, and citrus fruits on the symptoms of gastroesophageal reflux diseases. PUBLIC HEALTH RELEVANCE: This study has an important public health implication because 1) it examines the effects of diet, one of the most modifiable risk factors on the risk of esophageal adenocarcinoma, a cancer that is increasing in its incidence rapidly, and 2) it evaluates the effects of food items that are commonly thought to affect acid reflux, a symptom from which a large proportion of Americans suffer.